1. Field of the Invention
The present invention relates in general to universal couplings, such as a coupling applied to a propeller shaft and the like, for wheeled motor vehicles, and more particularly to the universal couplings of a type that can be easily assembled without inducing undesirable blocking of an air bleeding passage that provides a fluid communication between the inside of the coupling and the outside of the same.
2. Description of Related Art
In order to clarify the task of the present invention, one known universal coupling will be briefly described in the following, which is disclosed in Japanese Utility Model Provisional Publication (Jikkaisho) 61-117921.
The universal coupling of the publication generally comprises a torque transmitting unit through which two shafts are connected. A boot extends between the two shafts while covering the torque transmitting unit. For connection with the shafts, each axial end of the boot has a connecting mouth. The interior of the boot is filled with a grease for lubricating elements of the torque transmitting unit.
For releasing an undesired pressure inevitably produced in the boot due to thermal expansion of the interior of the boot, there is provided an air bleeding passage between one of the shafts and the corresponding connecting mouth of the boot. For protecting the air bleeding passage from sludge, water and the like, a boot cover is connected to the shaft in a manner to cover the connecting mouth of the boot while keeping a certain clearance therebetween.